1. Field of the Invention
The present general inventive concept relates generally to addressing problems posed by runoff from rainfall, snowmelt and other sources (collectively referred to herein as “runoff” or “stormwater runoff”) particularly where unmitigated runoff can pose multiple threats. Specifically, if unabated, runoff can carry harmful pollutants to rivers, streams and bays, as well as bypass the natural process of groundwater or aquifer replenishment. This disclosure proposes a novel solution to unabated runoff embodied as a system and method that apply equally as well to runoff from urban, industrial, agricultural and residential slopes so as to avoid property destruction, erosion, environmental pollution and the like, as well as enhance diminishing aquifer levels.
2. Description of the Related Art
Melted snow and rain water, when not evaporated or directly channeled to tributaries, lakes, bays and oceans, can be expected to deliver seriously deleterious impact on properties and systems ranging from residential housing tracts to industrial and recreational parks, water reservoirs and wastewater treatment facilities. This melted snow or rainwater, or runoff, carries with it the potential for landscape erosion and property destruction and the unwelcome transport of a variety of pollutants with considerable risk to human health and environment. Another serious problem is that rapid “off-flow” moves so quickly across terrain that depleted aquifers are rarely sufficiently recharged. Still worse, unabated runoff can take its toll on human lives as it overwhelms seawalls, undermines foundations, sweeps motor vehicles from highways and collapses bridges and dams.
Runoff can prove damaging in other ways apart from its persistent force. Even low volume or infrequent runoff can bring irreparable erosion to parkland and coastlines. Runoff issues most often discussed are in the context of rural and agricultural venues, yet the economic and environmental impacts are at least as great or even greater in urban, industrial and residential settings. The U.S. Environmental Protection Agency (see epa.gov) documents that stormwater from streets, parking lots, and other paved surfaces carries a considerable quantity of pollution directly into tributaries and waters there beyond. EPA reports that impervious surfaces of a city block generate five times more runoff than a wooded area of the same size. More specifically, EPA studies reveal the runoff/absorbed ratio for urban settings at 55%/15%. Contrastingly, for natural settings, the ratio is reversed. For both, the balance of approximately 30% of stormwater is evapotranspired, meaning that the remaining stormwater is transferred from the land to the atmosphere by evaporation from the soil and other surfaces.
Toxic materials in cityscape runoff can include dirty sediment, heating oil, automobile grease, antifreeze and brake fluid, rodent poisons, herbicides, pesticides and fertilizers from lawns and golf courses, parks and highways, pathogens and bacteria from pet waste and leaking septic systems, road salts and heavy metals—all naturally flushed from city streets and dispatched untreated into rivers, lakes, and bays. Worse still, are countless fatalities wrought by unexpected flash floods—the leading cause of weather-related deaths in the United States, approximately two hundred per year. See Floodsmart.gov.
Over the years, many stormwater capture and control concepts have been proposed and explored in both urban and rural settings but have enjoyed limited success for a number of reasons. Typically these control concepts focus on varied applications of (1) filter strips, (2) grass waterways and (3) wetlands (natural and constructed); each of which delivers unique advantages. In a manner of speaking, these concepts “hold water” only to a certain extent.
“Filter strips” generally are embodied as narrow, vegetative bands (grass or trees) strategically planted along edges of streams, rivers, and bays. Typically these narrow vegetative bands are planted in various widths—as narrow as twenty feet or as wide as several hundred feet. As stormwater runoff races across a landscape and subsequently passes through the filter bands, sediment and nutrients are captured within the strips thus preventing pollutants from migrating to streams, reservoirs and tidal waters. The problem with filter strip practice is that an unusually heavy rain event brings such a high flow rate of stormwater runoff that only a relatively small portion of the flowing pollutants can be captured. Moreover, since runoff may travel a considerable distance, perhaps miles, before encountering filter strips residing only along stream or bay edges, the significant baggage of accumulated pollutants simply cannot be effectively filtered.
“Grass waterways” (in some environs referred to as “floodways”) consist of relatively low grassy areas along which stormwater flows as it runs off city parks, sports stadium areas, shopping center parking lots and agricultural fields. Waterways are configured and strategically located to follow a declining grade ultimately leading to a stream/river/bay. This runoff control practice can be effective in preventing gullies or washout ditches from forming, thereby avoiding property damage and discouraging eroded sediment from being swept into stream/river/bay waters. Enhanced by plantings, “waterway vegetation” is judged somewhat effective as a natural filtering system accomplishing objectives essentially the same as filter strips. Unfortunately, both approaches generally fail in their filtering role in the face of heavy stormwater accumulations and the consequential acceleration of long distance runoffs.
“Wetlands” is the general name for natural or excavated land areas where water covers the soil or is present near the soil surface or within the root zone—at least for varying time periods. Recurrent or prolonged presence of water (hydrology) at the soil surface is the dominant factor determining the soil nature and types of plants living in the soil. Wetlands are characteristically defined by the presence of plants (hydrophytes) adapted to life in hydric soils subjected to flooded or saturated conditions. See Mitsch, W. J. and J. G. Gosselink, 1993; Wetlands, 2nd Ed. John Wiley & Sons; New York; 722 pp. Wetlands may be natural or human-made and more contemporaneously are valued for naturally handling high volumes of runoff, particularly near large cityscapes.
New Jersey's Department of Environmental Protection recently noted that wetlands were “previously misunderstood and typically destroyed as wastelands.” Regardless of name, they are now widely recognized for their vital ecological and socioeconomic contributions—such as enhanced and relatively inexpensive protection of drinking water by filtering out chemicals, pollutants, and sediments, and soaking up runoff from heavy rains and snow melts. See the 2015 Report, State of New Jersey's Division of Land Use Regulation.
Besides, wetlands often serve as buffers by slowing the flow of pollutants into tributaries and onward to larger bodies of water such as the Chesapeake Bay and its tributaries. As polluted stormwater runs off the agricultural land and passes through wetlands, the hydrophytes, e.g. trees and grasses native to the wetland soil, serve to filter and absorb nutrients, suspended sediments and chemical contaminants. See the Chesapeake Bay Program Watershed Project, Annapolis, Md. website at chesapeakebay.net/wetlds1.htm. On the other hand, wetlands do have their shortcomings. In their natural occurrence they are reasonably effective only when they happen to be strategically located with respect to flows of city and/or agricultural runoff. Constructed (or manmade) wetlands are extremely expensive to create, particularly considering the plantings involved. Similar to filter strips and waterways, a heavy rain event can deliver such heavy volumes of runoff that the resultant flow through the wetlands overrides its capacity to effectively address sediment and nutrients.
These widely popular “solutions” have fallen short of their good intentions, leading to the development of still other approaches. The patent literature reflects ongoing interest in developing commercializable systems to address the challenge of stormwater runoff pollution and contamination treatments as well as bolstering diminishing aquifers.
U.S. Pat. No. 5,823,711 granted to Herd et al. presents a system for trapping and recycling surface water containing treatment chemicals, particularly on golf courses and possibly farms. This patented drainage and collection system includes a graded channel in which is secured a water impervious liner covering the channel bottom and wall surfaces. Scrap automobile tire components are positioned within the channel and on top of the liner. The surface water percolates through and around the scrap tire components, runs down the grades of the liner, and collects within the reservoir. A pumping station cooperates with an irrigation system to recycle the water and chemicals back to the surface of the golf course or the like. The objective of the Herd system is the collection, storage, and recirculation of water and chemicals used to maintain the field area. Repeatedly recycled fertilizer-laden runoff, of course, has its own natural limitations in terms of continued effectiveness and scale of application.
Wengrzynek's U.S. Pat. No. 5,174,897 describes a staged construct comprising (in hydraulic order) a sediment basin, level-lip spreader, grassy filter, wetland, and deep pond. The combination of these elements acts to remove pollutants from nonpoint source runoff. Wetlands are planted with vegetation that encourages growth of aerobic and anaerobic bacteria helpful in removing and detoxifying contaminants. This would appear to be a grand scale approach, and essentially un-scalable.
In U.S. Pat. No. 5,330,651 entitled “Treatment of Contaminated Agricultural Runoff,” Canadian inventors Robertson, Blowers and Ptacek present a system of land drains to convey nitrate-polluted run-off water from a field to a reservoir. This reservoir would be large enough to contain excess quantities of stormwater run-off. From the reservoir, the water enters a collection tank containing submerged wood or other organic carbon material. The wood is kept under water, i.e., under anaerobic conditions, whereby nitrates are broken down by biochemical action. Sufficient wood is added and flow rate is adjusted such that the nitrate-polluted water spends many hours in contact with the wood. The objective is to provide a treatment for breaking down the nitrate in water washed off an agricultural field so that run-off water eventually passing away from the field is substantially nitrate-free. The Robertson et al. invention is mainly concerned with treating water that enters drainage ditches, land-drains. This system may or may not sufficiently treat the nitrate-laden water and does little or nothing with respect to accompanying pollutants, all of which then depart for the estuaries and coast.
Published Patent Application 2003/0019150 presents a “Reclamation System for Agricultural Runoff.” This patent application filed by St Onge and Smith relates to systems for collecting excess water applied to crops, treating the collected water and reusing the treated water for agricultural purposes, or delivering the treated water to ground water streams. The inventors' objective is to achieve cost savings, healthier plants, and reduce the environmental burden. The disclosed systems are said to significantly reduce costs incurred in providing water, nitrogen fertilizer, herbicides and/or pesticides to crops by capturing as much as possible of the water provided to the planting area which is not taken up by the planted crops, treating that captured water with ozone, and reapplying the ozone treated water to the crops. According to the patent applicants, the quality and quantity of food stuffs produced are increased by the process. This is another scheme for continuously recycling pollutants.
Harrison and Turnbull received U.S. Pat. No. 8,640,387 for a water harvesting system adapted to a sports arena where a playing surface operates as a part of a water catchment arrangement and reservoir beneath the playing surface. Water may be discharged from the reservoir for consumption or other uses. Stadium seating area is impervious so as to direct water toward the playing field for capture thereunder.
Nuzman received U.S. Pat. No. 4,254,831 for his method and apparatus for restoring and/or maintaining an underground aquifer water supply system plagued with decreased water flow attributable to accumulation of undesirable flow impeding agents in the aquifer. He presented a plurality of injection wells drilled in the ground in surrounding relationship to the production well and a part of the water from the discharge thereof is treated with an additive capable of altering the nature of the plugging agents and returned to the aquifer via the satellite injection wells on a continuous basis.
U.S. Pat. No. 8,152,997 was granted to Olson, Johnson and Langford related to stormwater control including conveyance, filtration and discharge systems. The conveyance system includes a set of conduits and connections providing a flow path through a compacted soil embankment from an upper inlet to a lower discharge area of an underlying soil infiltration zone. The control system has configurations for transferring stormwater from pervious and impervious surfaces to the soil infiltration zone. This control system optionally includes a media filter device that may be installed within the conveyance system to intercept sediment and other contaminants prior to discharge within the underlying soil infiltration zone.
In his U.S. Pat. No. 8,877,048, inventor Samuel Owings describes a series of cascading basins excavated along a sloped floodway typically established between adjoining agricultural fields. These basins address problems of stormwater runoff from agricultural lands and certain urban areas where runoff carries sediment, nitrogen, phosphorous and other pollutants into nearby streams, rivers and tidal waters. The cascading basin series begins with basin placement at a higher topographical elevation, then positioning additional basins downwardly along a natural or excavated floodway slope demonstrating a terraced effect. As an upper basin is filled it overflows into a second basin terraced therebelow. Overflow of the second and sequential basins continues down-slope. Thoughtfully configured, angular features of basin exit grade and escape slopes retard egress of stormwater. A lowermost terminal basin selectively includes sand berm, boulders, rip rap (loose stones) and other barriers to retain the polluted runoff. Basins may include vegetation, slag stone layers, and other pollutant treatment elements.
In U.S. Pat. No. 8,333,895, patentee Albers and Amell describe a runoff capturing pond with a tangential entry point and central outlet. The capturing pond initially contains a volume of clarified water. Contaminated runoff is directed through the entry point and proceeds to displace the clarified water in an inward spiral toward the outlet where it is discharged. This results in an increased residence time for the contaminated water to become treated and settled.
Inventors Carter and Wiser received U.S. Pat. No. 3,429,806 depicting a series of recycling stabilization treatment ponds positioned on a downhill slope, ultimately leading to a final aeration pond from which overflow is discharged to a stream.
Published US Patent Application 20130299403 filed by Susannah Drake discloses a system for reducing runoff from an urban area into a body of water. In one embodiment, water flows from a sedimentation basin and into plurality of bio-retention cells, each extended at an angle relative to the sedimentation basin. Overflow water flows from the plurality of bio-retention cells into an elongated filter. In another embodiment, a system for reducing run off from an elevated road is disclosed. The system includes an enclosure with a sedimentation basin and a bio-filtration basin.
In his U.S. Pat. No. 3,556,026 Houston describes a farming method to conserve available rainfall comprising the forming of a plurality of elongated, spaced-apart, open-top slots in the soil surface and the construction of laterally extending, moisture transfer retarding barriers adjacent the slots to force rainfall from the adjacent field area into the slots. The slots are mulched to the top to minimize moisture loss through evaporation. The moisture transfer retarding barriers are formed by working the soil surface to enhance crusting, treating the soil with chemicals which congeal the soil, or by placement of water impervious sheet material.
Madrid received U.S. Pat. No. 6,712,969 for a method of phosphorous reduction in stormwater runoff using iron humate, such as in the form of a filter, a layered filter bed, a stacked wall or a liner. The stormwater (fluid) runoff is sent to a fluid retention area such as a retention pond, wetland reservoir or the like where the runoff is filtered through iron humate. While the runoff is filtered, the iron humate absorbs or chemically retains the phosphorous in the runoff to produce filtered runoff with a reduced level of phosphorous. In an alternate embodiment, the runoff can be pumped from a retention pond into a iron humate filter where the runoff is filtered. In another alternate embodiment, the iron humate filter may be placed in a trench below ground to intercept and filter groundwater flows.
McPhillips filed US Published Patent Application 20050161407 disclosing various compositions, devices and methods for use in a variety of environmental remediation barriers such as fiber rolls, mats, blankets and berms. He proposes applications for use including remediation of runoff water, livestock waste, eutrophication waterways and revetment of banks.
Each of the aforementioned patent grants and published applications is purposed to capture and treat run-off pollutants, and in some instances to recycle run-off water. For the record, each of the above discussed patent documents, in its entirety, is incorporated herein by reference.